Inhibitory kinetics and mechanism of kaempferol on α-glucosidase

alpha-Glucosidase is a therapeutic target for diabetes mellitus, and alpha-glucosidase inhibitors play a vital role in the treatments for the disease. As a kind of potentially safer alpha-glucosidase inhibitor, flavonoids have attached much attention currently. In this study, kaempferol was found to show a notable inhibition activity on alpha-glucosidase in a mixed-type manner with IC50 value of (1.16 +/- 0.04) x 10(-5) mol L-1. Analyses of fluorescence, circular dichroism and Fourier transform infrared spectra indicated that kaempferal bound to alpha-glucosidase with high affinity which was mainly driven by hydrogen bonds and van der Waals forces, and this binding resulted in conformational alteration of alpha-glucosidase. Further molecular docking study validated the experimental results. It was proposed that kaempferol may interact with some amino acid residues located within the active site of alpha-glucosidase, occupying the catalytic center of the enzyme to avoid the entrance of p-nitrophenyl-alpha-D-glucopyranoside and ultimately inhibiting the enzyme activity. (C) 2015 Elsevier Ltd. All rights reserved.